Log data management system having a plurality of processing units and a common memory

Abstract

A log data management system is used with a database processing system. The log data management system has a plurality of database update units coupled to a database through a common bus. Each of the database update units updates a resource of the database and records log data as an update record. The database update unit writes log data of the resource of the database in a local memory in order of update time of the resource. After the resource has been updated, the database update unit transfers the log data written in the local memory to the common memory. At this time, since the database update unit does not free the resource until the log data is non-volatilized in the common memory, log data are successively stored in the common memory in order of the update time of the resource. When a failure takes place in a resource of the database, log data stored in the common memory are referred to and thereby the resource is quickly closed and recovered.

What is claimed is: 
     
       1. A log data management method including a plurality of database update units, each of said database update units being adapted to access a database through a common bus, exclusively update a resource of said database, and get log data as an update data, said method comprising steps of: getting said log data; and   storing said log data to a non-volatile common area in order of update time of said resource when said resource is released after said resource has been updated, said common area being shared by said database update units.   
     
     
       2. The log data management method as set forth in claim 1, further comprising steps of: acquiring an exclusive use right of said resource before said resource is updated; and   discarding said exclusive use right of said resource after said log data has been stored in said common area.   
     
     
       3. A log data management method including a plurality of database update units, each of said data-base update units being adapted to access a database through a common bus, exclusively update a resource of said database, and get log data as an update data, said method comprising steps of: getting said log data;   storing said log data to a first common area in order of update time of said resource after said resource has been updated, said first common area being shared by said database update units;   compressing said log data stored in said first common area; and   storing the compressed log data to a second common area when said resource is released, said second common area being shared by said database update units and non-volatilizing the compressed log data.   
     
     
       4. The log data management method as set forth in claim 3, further comprising steps of: acquiring an exclusive use right of said resource before said resource is updated; and   discarding said exclusive use right of said resource after said log data has been stored in said second common area.   
     
     
       5. A log data management method including a plurality of database update units, each of database update units being loosely coupled and being adapted to access a database, exclusively update a resource of said database, and get log data as an update data, said method comprising steps of: getting said log data; and   storing said log data to a non-volatile common area in order of update time of said resource when said resource is released after said resource has been updated, said common area being shared by said database update units.   
     
     
       6. A log data management method for recording log data of a database accessed by a plurality of systems, comprising steps of: getting said log data of said database shared by said systems when said database has been exclusively updated; and   writing said log data to a non-volatile common memory in order of update time of said database when said database is released.   
     
     
       7. A log data management method for recording log data of database accessed by a plurality of systems, comprising steps of: getting log data of said database shared by said systems when said database has been exclusively updated;   writing said log data to a volatile common memory in order of update time of said database;   buffering said log data gotten by said systems in a lump thereby increasing space efficiency; and   writing the buffered log data to a non-volatile log file when said database is released.   
     
     
       8. A database recovering method for recovering a defective resource of a database with log data, said log data being gotten as an update data by a plurality of database update units that access said database through a common bus when said database update units exclusively update said resource, said database recovering method comprising steps of: storing said log data in a non-volatile common area shared by said database update units in order of update time of said resource when said resource is released before a failure takes place in said resource; and   recovering said defective resource with said log data stored in said common area when said failure takes place.   
     
     
       9. A computer-readable storage medium, when used by a database processing system including a plurality of computers being adapted to access a database through a common bus, exclusively update a resource of said database and get log data as an update data, used to perform the functions of: getting said log data; and   storing said log data to a non-volatile common area in order to update time of said resource when said resource is released after said resource has been updated, said common area being shared by said computers.   
     
     
       10. A log data management system for use with a database processing system having a plurality of processing units linked by a common bus, said processing units being adapted to exclusively update a resource and to get log data as an update data, said log data management system comprising: a database for storing said resource; and   common memory means of a non-volatile type, for storing said log data obtained by said processing units in order of update time of said resource after said resource has been updated by one of said processing units, said log data being non-volatilized in said common memory means when said resource is released.   
     
     
       11. The log data management system as set forth in claim 10, wherein said common memory means is storing means having a control data area by which accesses from said processing units are controlled.   
     
     
       12. The log data management system as set forth in claim 10, wherein said one of said processing units is adapted not to permit other processing units to use said resource until said log data is stored in said common memory means.   
     
     
       13. A log data management system having a plurality of database update units linked with a database through a common bus, said database update units being adapted to exclusively update a resource of said database and to get log data as an update data, said log data management system comprising: common memory means of a non-volatile type, linked with said database update units,   wherein each of said database update units comprises:   local memory means for storing said log data in order of update time of said resource; and   log data transferring means for transferring said log data stored in said local memory means to said common memory means after said resource has been updated, and   wherein said common memory means is adapted to store said log data transferred from said database update units in order of update time of said resource in a lump, said log data being non-volatilized in said common memory means when said resource is released.   
     
     
       14. The log data management system as set forth in claim 13, wherein said common memory means is storing means having a control data area by which accesses from said database update units are controlled.   
     
     
       15. The log data management system as set forth in claim 13, wherein each of said database update units is adapted not to permit other database update units to use said resource until said log data is stored in said common memory means.   
     
     
       16. A log data management system for use with a database processing system having a plurality of database update units linked with a database through a common bus, said database update units being adapted to exclusively update a resource of said database and to get log data as an update data, said log data management system comprising: common memory means for compressing and storing said log data gotten by said database update units in order to update time of said resource after said resource has been updated by one of said database update units; and   log non-volatilizing means for non-volatilizing said log data stored in said common memory means when said resource is released.   
     
     
       17. The log data management system as set forth in claim 16, wherein said common memory means is volatile storing means, and   wherein said log non-volatilizing means is non-volatile storing means linked with said common bus.   
     
     
       18. The log data management system as set forth in claim 16, wherein said one of said database update units is adapted not to permit other database update units to use said resource until said log data is non-volatilized by said log non-volatilizing means.   
     
     
       19. A log data management system having a plurality of database update units linked with a database through a common bus, said database update units being adapted to exclusively update a resource of said database and to get log data as an update data, said log data management system comprising: common memory means linked with said database update units; and   log non-volatilizing means linked with said database update units,   wherein each of said database update units comprises: local memory means for storing said log data in order to update time of said resource; and   log data transferring means for transferring said log data stored in said local memory means to said common memory means after said resource has been updated,   wherein said common memory means is adapted to compress and store said log data transferred from said database update units in order of update time of said resource in a lump, and   wherein said lot non-volatilizing means is adapted to non-volatilize said log data stored in said common memory means when said resource is released.     
     
     
       20. The log data management system as set forth in claim 19, wherein said common memory means is volatile storing means, and   wherein said log non-volatilizing means is non-volatile storing means linked with said common bus.   
     
     
       21. The log data management system as set forth in claim 19, wherein each of said database update units is adapted not to permit other database update units to use said resource until said log data is non-volatilized by said log non-volatilizing means.   
     
     
       22. A database update unit for use in a database processing system having a plurality of database update units linked with a database through a common bus, said database update units being adapted to exclusively update a resource of said database and to get log data as an update data, said database update unit comprising: local memory means for storing said log data in order of update time of said resource; and   log data transferring means for transferring said log data stored in said local memory means to a common memory linked with said database update units, said common memory being adapted to store said log data transferred from said data database update units in order of update time of said resource in a lump, said log data being non-volatilized in said common memory when said resource is released.   
     
     
       23. The database update unit as set forth in claim 22, further comprising: control means for controlling contention with other database update units, said contention taking place when said log data transferring means transfers said log data to said common memory.   
     
     
       24. A database update unit for use in a database processing system having a plurality of database update units linked with a database through a common bus, said database update units being adapted to exclusively update a resource of said database and to get log data as an update data, said database update unit comprising: local memory means for storing said log data in order of update time of said resource; and   log data transferring means for transferring said log data stored in said local memory means to a common memory linked with said database update units, said common memory compressing and storing said log data in order of update time of said resource, and for storing the compressed log data in a log non-volatilizing area when said resource is released.   
     
     
       25. The database update unit as set forth in claim 24, further comprising: control means for controlling contention with other database update units, said contention taking place when said log data transferring means transfers said log data to said common memory.   
     
     
       26. A log data management system having a plurality of database update units linked with a database through a common bus, a transaction taking place in said database update units, said transaction being adapted to update a resource of said database and to record log data as an update record, said log data management system comprising: common memory means of a non-volatile type, linked with said database update units,   wherein each of said database update units comprises: exclusion control means for allowing said transaction to exclusively use said resource;   log data getting means for allowing said transaction to get said log data in order of update time of said resource; and   log writing means for writing said log data to said common memory after said resource has been updated, and   wherein said exclusion control means is adapted to allow another transaction to use said resource after said log writing means has written said log data to said common memory means.     
     
     
       27. A log data management system having a plurality of database update units linked with a database through a common bus, a transaction taking place in said database update units, said transaction being adapted to update a resource of said database and to record log data as an update record, said log data management system comprising: common memory means linked with said database update units,   wherein each of said database update units comprises: exclusion control means for allowing said transaction to exclusively use said resource;   log data getting means for allowing said transaction to get said log data in order to update time of said resource;   log writing means for writing said log data to said common memory after said resource has been updated; and   log non-volatilizing means linked with said database update units and adapted to non-volatilize said log data,     wherein said common memory means is adapted to compress said log data, and   wherein said log writing means is adapted to write the compressed log data to said log non-volatilizing means, and   wherein said exclusion control means is adapted to allow another transaction to use said resource after said log writing means has written said log data to said log non-volatilizing means.   
     
     
       28. A log data management system for use with a loosely coupled database processing system having a plurality of processing units, each of said processing units being adapted to exclusively update a resource and get log data as an update data, said log data management system comprising: a database for storing said resource; and   common memory means of a non-volatile type, for storing said log data gotten by said processing units in order of update time of said resource after said resource has been updated by one of said processing units, said log data being non-volatilized in said common memory means when said resource is released.   
     
     
       29. A log data management system for use with a loosely coupled database processing system having a plurality of database update units linked with a database, each of said database update units being adapted to exclusively update a resource of said database and get log data as an update data, said log data management system comprising: common memory means for compressing and storing said log data gotten by said database update units in order of update time of said resource after said resource has been updated by one of said database update units; and   log non-volatilizing means for non-volatilizing said log data stored in said common memory means when said resource is released.   
     
     
       30. A database update unit for use in a loosely coupled database processing system having a plurality of database update units linked with a database, each of said database update units being adapted to exclusively update a resource of said database and get log data as an update data, said database update unit comprising: local inemory means for storing said log data in order of update time of said resource when said resource is updated; and   log data transferring means for transferring said log data stored in said local memory means to a common memory linked with said database update units, said common memory being adapted to store said log data transferred from said database update units in order of update time of said resource in a lump, said log data being non-volatilized in said common memory when said resource is released.   
     
     
       31. A database update unit for use in a loosely coupled database processing system having a plurality of database update units linked with a database, each of said database update units being adapted to exclusively update a resource of said database and get log data as an update data, said database update unit comprising: local memory means for storing said log data in order of update time of said resource when said resource is updated; and   log data transferring means for transferring said log data stored in said local memory means to a common memory linked with said database update units, said common memory compressing and storing said log data in said common memory in order of update time of said resource, and for storing the compressed log data to a log non-volatilizing area when said resource is released.   
     
     
       32. A database recovering system for recovering a failure of a database with log data, said log data being gotten as an update data by a plurality of database update units linked with said database through a common bus when a resource of said database is exclusively updated by said database update units, said database recovering system comprising: common memory means of a non-volatile type, linked with said database update units and for storing said log data gotten by said database update units in order of update time of said resource before said failure takes place, said log data being non-volatilized in said common memory means when said resource is released; and   recovering means for recovering said resource with said log data stored in said common memory means when said defect takes place in said resource.